Dr. Justin Congdon - Savannah River Ecology Lab

Evolution of Life Histories, Indeterminate Growth, and Perceptions of Age in Turtles

The singular life-history trait of attaining maturity combined with the relative contributions of juvenile and adult growth combine to shape the suite of life-history traits of organisms with indeterminate growth. Although the assumption that indeterminate growth is a general trait of reptiles is widely accepted, data are scarce (particularly for long-lived individuals.)

We examined patterns of variation in adult growth using over a hundred years of mark-recapture data on 13 populations of 9 species (3 families) of freshwater turtles from studies in South Carolina, Michigan, and Arizona in the USA and in Ontario, Canada. The influence of growth on life-history trait values indicated that increases in body size (and associated reproductive output) resulting from indeterminate growth are not substantial enough to represent a major factor in the evolution of life histories in general or the evolution of longevity and aging specifically.